WA Online Multiscale Peak Detection VI

LabVIEW 2014 Advanced Signal Processing Toolkit Help

Edition Date: June 2014

Part Number: 372656C-01

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Owning Palette: Online Wavelet Analysis VIs

Requires: Advanced Signal Processing Toolkit

Uses multiresolution wavelet analysis to detect peaks or valleys in a streaming signal. Wire data to the signal input to determine the polymorphic instance to use or manually select the instance.

Note  Use this VI to detect peaks or valleys in a streaming signal. For offline wavelet analysis, use the WA Multiscale Peak Detection VI.

Details  Examples

Use the pull-down menu to select an instance of this VI.

WA Online Multiscale Peak Detection (Waveform)

initialize? specifies whether to initialize the internal state of the block of data to zero. The default is FALSE. When the value is TRUE, this VI initializes the internal state to zero and processes one block of data. When the value is FALSE, this VI initializes the internal states to the final states by using the previous call to this VI instance.

To process consecutive blocks of data, set initialize? to TRUE for the first block and FALSE for all other blocks of data.
peaks/valleys specifies whether this VI looks for peaks or valleys in the signal. The default is peaks.
signal specifies the input signal.
threshold specifies the threshold this VI uses to reject peaks or valleys of a particular size. If this VI looks for peaks, this VI ignores peaks with a peak amplitude less than threshold. If this VI looks for valleys, this VI ignores valleys with a valley amplitude greater than threshold. If detrend? is TRUE, this VI rejects peaks or valleys below the threshold in the detrended signal. If detrend? is FALSE, this VI rejects peaks or valleys below the threshold in the signal.
width specifies the width, in number of samples, of the peaks or valleys. This VI coerces the value to a power of 2.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
detrend settings specifies the settings this VI uses to remove the trend from the signal.
detrend? specifies whether this VI removes the trend from the signal. The default is FALSE, which means this VI does not remove the trend.
threshold frequency specifies the upper frequency limit, in hertz, of the trend that this VI removes from the signal. The threshold frequency determines the wavelet transform level. The wavelet transform level specifies the number of levels in the discrete wavelet analysis, where more levels result in a longer delay when you run this VI. The wavelet transform level is floor(log2[sampling rate/(2*threshold frequency)]). The floor function rounds a value to the nearest integer towards negative infinity. The default is –1, which means this VI sets the threshold frequency as sampling rate/4.
location returns the locations of the peaks or valleys this VI detects.
amplitude returns the amplitudes of the peaks or valleys this VI detects.
peak plot returns the signal and the peaks or valleys this VI detects. If detrend? is TRUE, peak plot also returns the trend of the input signal. You can plot this information on an XY graph.
error out contains error information. This output provides standard error out functionality.

WA Online Multiscale Peak Detection (Array)

initialize? specifies whether to initialize the internal state of the block of data to zero. The default is FALSE. When the value is TRUE, this VI initializes the internal state to zero and processes one block of data. When the value is FALSE, this VI initializes the internal states to the final states by using the previous call to this VI instance.

To process consecutive blocks of data, set initialize? to TRUE for the first block and FALSE for all other blocks of data.
peaks/valleys specifies whether this VI looks for peaks or valleys in the signal. The default is peaks.
signal specifies the input signal.
threshold specifies the threshold this VI uses to reject peaks or valleys of a particular size. If this VI looks for peaks, this VI ignores peaks with a peak amplitude less than threshold. If this VI looks for valleys, this VI ignores valleys with a valley amplitude greater than threshold. If detrend? is TRUE, this VI rejects peaks or valleys below the threshold in the detrended signal. If detrend? is FALSE, this VI rejects peaks or valleys below the threshold in the signal.
width specifies the width, in number of samples, of the peaks or valleys. This VI coerces the value to a power of 2.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
detrend settings specifies the settings this VI uses to remove the trend from the signal.
detrend? specifies whether this VI removes the trend from the signal. The default is FALSE, which means this VI does not remove the trend.
threshold frequency specifies the upper frequency limit, in hertz, of the trend that this VI removes from the signal. The threshold frequency determines the wavelet transform level. The wavelet transform level specifies the number of levels in the discrete wavelet analysis, where more levels result in a longer delay when you run this VI. The wavelet transform level is floor(log2[sampling rate/(2*threshold frequency)]). The floor function rounds a value to the nearest integer towards negative infinity. The default is –1, which means this VI sets the threshold frequency as sampling rate/4.
sampling rate specifies the sampling rate of signal in hertz. sampling rate must be greater than 0, or this VI sets sampling rate to 1 automatically. The default is 1.
location returns the locations of the peaks or valleys this VI detects.
amplitude returns the amplitudes of the peaks or valleys this VI detects.
peak plot returns the signal and the peaks or valleys this VI detects. If detrend? is TRUE, peak plot also returns the trend of the input signal. You can plot this information on an XY graph.
error out contains error information. This output provides standard error out functionality.

WA Online Multiscale Peak Detection Details

This VI executes steps similar to the WA Multiscale Peak Detection VI to detect peaks by using a wavelet-based method. Refer to the Details section of the WA Multiscale Peak Detection VI for more information about how this VI detects peaks.

Examples

Refer to the following VIs for examples of using the WA Online Multiscale Peak Detection VI:

  • ECG Heart Rate Monitor (Online) VI: labview\examples\Wavelet Analysis\WAApplications
  • Online Peak Detection and Display in Strip Mode VI: labview\examples\Wavelet Analysis\WAGettingStarted
  • ECG QRS Complex Detection VI: labview\examples\Wavelet Analysis\WAApplications

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